Most paradoxically (or so it seems): How, both professionally and romantically, Kim long ago threw in with fellow lawyer Jimmy McGill, the series' hero played by Bob Odenkirk, a freewheeling rascal who cuts corners with such gusto his squares become circles.

He, of course, will eventually double down on his duplicity by rebranding himself Saul Goodman and serving a key role in the meth-making mayhem of "Breaking Bad" (which aired from 2008 to 2013). But in "Saul," the prequel of "Breaking Bad," Jimmy's soul remains in play as Kim appeals to his better nature, and he to hers.

"There's a lot of history between them, but also a lot of boundaries," says Rhea Seehorn, who plays Kim. "It isn't flirting and sexual in a superficial way. There's a rich friendship and a real respect going back and forth.

"Kim is a conduit for the audience for what they love about him," she adds. "No viewers want to think about how someday, as Saul, he will order hits on people, but we do love that Jimmy colors just outside the lines remarkably well.

"I don't look at each season of 'Better Call Saul' as a countdown to 'Breaking Bad,' thinking: 'We're this much closer to him being Saul.' But in season three you get more glimpses of Saul emerging in Jimmy. This transformation is heartbreaking.

"But he's still a great lawyer," she insists. "And a great thinker."

As "Saul" returns for its third season Monday at 10 p.m. EDT on AMC, Kim, too, remains a great lawyer, a great thinker and her own breed of enigma. No wonder that, for Seehorn, playing Kim has been a learning process from the start.

Rhea (pronounced "Ray") Seehorn became an actress to learn: "I was obsessed with trying to figure out people psychologically who aren't me," she says, "and walk in their shoes for a while."

In person, her shoes are clearly different from Kim's: stylish boots, not office-suited heels. Her blond hair cascades past her shoulders, freed from Kim's strict ponytail. She flashes a dazzling smile almost never displayed by the meditative Kim, whose introspective bearing strikes a marked contrast to Seehorn's vivacious manner.

She had logged stage credits on and off Broadway, and supporting roles on the sitcom "Whitney" and the lighthearted drama "Franklin & Bash," when she tried out for "Better Call Saul."

To guard against leaks, the producers were keeping any actual scenes from the show, and even details of the role Seehorn was seeking, tightly under wraps.

Here's Seehorn describing the scene she was given by the casting directors: "I was a policewoman on her way home, exhausted, after her night shift who sees a disturbance in an alley. She thinks it involves a prostitute and drugs, but it turns out to be her own sister, whose tuition she was paying to send her to school in another state!"

As Seehorn later realized, "The scene served as a showcase for traits that could be grafted onto the Kim Wexler character: the workaholic part of Kim; the need to maintain control; dealing with a personal versus a professional relationship. They wanted to see: Can I do this? Can I do that? And we did it many, many ways.

"I had a blast! But it makes you sweat a lot. I wore a sleeveless blouse for all the auditions."

In all, there were three auditions, the final one alongside Odenkirk.

Even then, Seehorn knew little other than the part she was seeking was a lawyer. She had no idea what the character's connection with Jimmy might be, no clue as to the size of the role.

"But who cares? Even if you have a small part in a brilliant play, it's gonna be a great part!"

Needless to say, Seehorn found her place front and center in the action. But she, along with the audience, continues to discover who Kim is, script by revealing script, episode by episode.

"You play the scene that's right in front of you. There's no looking ahead," she says. "It's not that the producers are manipulative. You're not like a marionette and they know everything but just won't tell you, so they can make you dance faster. They're mapping out the world as they go, just like you are."

Along the way, the connection between Kim and Saul continues to defy any easy explanation.

"Putting a label on it is not only not the point, but a disservice to what is going on between them," says Seehorn. "It's not that simple."

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EDITOR'S NOTE — Frazier Moore is a national television columnist for The Associated Press. He can be reached at fmoore@ap.org. Past stories are available at http://bigstory.ap.org/content/frazier-moore